Fellow guard player here,
It's easy to get bogged down building lot of squads and buying tons of kits for
IG, so my best advice is to do as much forum reading as you can and purchase wisely. Lots of people have varying opinions on what works and what does not but in general there are a few long-running strategies for playing guard.
It looks like you are leaning towards playing with mechanized vets instead of large blobs of infantry, which is a very common and some would say competitive way to go. My opinions on what is worth taking in the codex is something like this:
HQ:
CCS's Yes! Very good, cheap source of orders and adviser buffs. Keeping them cheap/safe is the priority.
Pask Tank Commander: Punisher, with las cannon and
MM's backed by an executioner escort with plasma sponsons is pretty reliable damage output, just once again do not leave them unsupported.
I would not take named characters in
CCS, as they do not give you as much bang for your buck as their cost implies.
Elites:
Scions: They sort of fit the same role as veterans but are better if you have the means to deep strike them or air drop them. They also have access to their own orders but I tend to find them a bit expensive. I would use them if you have a reliable means of getting them to their target fast. Either Valkyrie or Taurox.
Bullgryns: Most people don't like using these, but I have fund them useful as a way of protecting my
CCS and/or artillery.
Troops:
Arguably the best section of the codex, lots of choices and variety.
Platoons are great for foot-slogging hordes with lots of heavy weapons, special weapons and cheap disposable bodies. The downside is just how easily countered they are by anti infantry weapons. They should always, always be buffed by priests or psychers, and the
PCS that comes with them is a good way to get a 4 flamer unit to drop in your opponent's backfield. I must warn you, going with large blobs may seem fun but when you look at the cost, time spent painting/assembling and then playing the game its a huge pain in the neck. I was foolish enough to do this and after painting 70+ almost identical guardsmen to what I consider a good standard I was just about ready to quit the hobby...
Veterans: Excellent way to fetch objectives, go tank hunting and advance up the board with special weapons.
Fast Attack:
I only use the fliers, Valk for transport and general air support, Vendetta for vehicle hunting/
AA.
Banewolf and the other flamer tanks could be very effective against hordes as well.
Sentinels are good weapons platforms and pretty fast. In addition, if you give them the relay you can deep strike your scions in the backfield. They are very fragile though.
Heavy Support:
Leman Russes are great. Battle tank for shelling from a distance, Demolisher with
MM sponsons for assaulting. I would stay away from vanquishers and exterminators.
Wyvern: Yes, yes, yes! Arguably our best unit for the cost. Get at least two!
Manticore/deathsrike: Some people swear by these, but to me they are high risk/high reward. If they hit they can decimate the opponent, if they miss you are wasting big points. For the price of one you can have 2 wyverns and points to spare so I say go for wyverns!
This is my opinion fro playing, researching guard for a while now. Hope this helps!